Research On LoS-MIMO Spatial Multiplexing Technology Of Millimeter Wave Communication

This thesis mainly studies the spatial multiplexing technology of millimeter-wave Multiple Input Multiple Output(MIMO)communication system in Line-of-Sight(LoS)environment.In a millimeter-wave LoS-MIMO communication system,the use of antenna selection technology can reduce hardware costs while ensuring system performance.In addition,the optimal design of the array antenna spacing can increase the orthogonality between sub-channels and the rank of the channel matrix,so as to improve the spatial multiplexing of LoS-MIMO channels.To sum up,this thesis will study and analyze the communication system model and channel capacity,antenna selection technology,and antenna array optimization design under the millimeter wave LoS-MIMO spatial multiplexing technology.Firstly,starting from the millimeter wave LoS-MIMO channel model,the channel capacity when the number of antennas at the transceiver end is different is deduced,and three kinds of uniform antenna geometric arrays commonly used at the transceiver end of the system are analyzed and introduced,and a uniform linear array(ULA),uniform plane array(UPA),uniform circular array(UCA)when the transceiver ends are parallel to each other and the alignment and the receiving end are in a misaligned state.The channel matrix formula simulates the influence of the receiver angle on the channel capacity under different misalignment conditions.Secondly,the transmitter antenna selection technology of millimeter wave LoS-MIMO communication system is studied,the exhaustive search algorithm and principal component analysis algorithm are analyzed,and the tabu search algorithm that can achieve the compromise between channel capacity and computational complexity is proposed,and the algorithm complexity of three antenna selection technologies is compared.The number of transmit antennas selected under different transmission distances and the channel capacity of different algorithms based on ULA and UPA are simulated and analyzed respectively.The tabu search algorithm can achieve the same performance as the exhaustive search algorithm,and it is always better than the principal component analysis algorithm.Especially under the large-scale antenna,the advantage is more obvious.Compared with the full antenna,the tabu search algorithm proposed in this thesis saves the hardware cost and increases the channel capacity steadily,and can control the iteration times of the tabu search algorithm to make the channel capacity achieve a compromise between high performance and low power consumption or achieve optimum performance.Finally,the optimal design of the antenna array of the millimeter wave LoS-MIMO communication system is studied.Based on the analysis of the importance of the optimal design of the millimeter wave LoS-MIMO antenna array,the optimal antenna spacing of ULA and UPA and the optimal diameter of UCA are given.In order to realize the channel capacity with small local drop within the Rayleigh distance,an antenna array arrangement method based on particle swarm optimization algorithm is proposed,and the non-uniform array arrangement after the optimal design of linear antenna array,planar antenna array and circular antenna array is given respectively.The particle swarm optimization algorithm proposed in this thesis is more stable than ULA,UPA and UCA in the optimization design based on antenna array,and the whole is closer to the theoretical maximum value of channel capacity.